He reigned from 1627 to 1644, under an era name that means "honorable and auspicious".

Born Zhu Youjian (朱由檢), Chongzhen was the fifth son of the Taichang Emperor. As such, he grew up in a relatively quiet environment, since most of the youngers sons were left out of the power struggle that their elder brother the Tianqi Emperor had to endure. Chongzhen succeeded his brother to the throne at age 17 and immediately eliminated the eunuch Wei Zhongxian and Madam Ke, who had become de facto rulers of the empire.
Chongzhen tried to rule by himself and did his best to salvage the dynasty. However, years of internal corruption and an empty treasury made it almost impossible to find capable ministers to fill important government posts. Chongzhen also tended to be suspicious of the few skilled subordinates he did have, executing the famous general Yuan Chonghuan, who had almost single-handedly maintained the northern frontier against the Manchus, in 1630.

The collapse of the Ming intensified during Chongzhen's reign. Popular uprisings broke out throughout China, including those of Zhang Xianzhong and the more important Li Zicheng. These could not be put down by the already hard-pressed Ming armies, who had to contend with the Manchu threat to the north.

In April 1644, Li prepared to take the Ming capital of Beijing. Rather than face capture and probable execution at the hands of the newly-proclaimed Shun Dynasty, Chongzhen gathered all members of the imperial household aside from his sons and ordered them to commit suicide. All did aside from one of his daughters, Princess Changping; the emperor ordered her arm severed in retaliation. Then, still wearing his imperial attire, Chongzhen fled to Jingshan Hill and hanged himself on a tree. He was buried in Siling of the Ming Dynasty Tombs - the last to be buried there.

The Shun Dynasty lasted less than year until Li's defeat at the Battle of Shanhai Pass, with the victorious Manchus establishing the Shunzhi Emperor of the Qing Dynasty as ruler of all China.

After Chongzhen's death, loyalist forces had proclaimed a Southern Ming Dynasty in Nanjing, naming Zhu Yousong, Prince of Fu as the Hongguang Emperor. However, in 1645 Qing armies started to move against the remnants of the Ming, and Nanjing surrendered in June 8, 1645. Zhu was captured on June 15 and brought to Beijing, where he died the following year. The dwindling Ming were continually pushed further south, and the last Emperor of the Southern Ming, Zhu Youlang, Prince of Gui, was finally executed in Burma in 1662 by Qing general Wu Sangui.

While Chongzhen was not especially incompetent by the standards of the later Ming- most direct blame for the dynasty's fall being laid at the feet of the Wanli Emperor- he has been criticized by his paranoia and inflexibility. Chongzhen's attempts at reform did not take into account the considerable decline of Ming power, which was already far advanced at the time of his accession. His betrayal of Yuan Chonghuan, in particular, has greatly damaged his contemporary reputation.